This invention relates to a novel structure for a strain relief device for attachment to a terminal connector for an optical fiber or an optical fiber ribbon. More particularly, this invention is directed to an enhanced multifiber boot that is capable of being installed by automated assembly and that has improved ribbon retention.
Optical fiber ribbons may include one or more optical fibers capable of transmitting audio, video, text, or other information. Optical fiber ribbons are laid over long distances and must make twists and turns, and, therefore, require connectors to connect discrete segments of optical fiber ribbons together or to connect an optical fiber ribbon to a terminal or signal port of an apparatus or other equipment. As used herein, the term xe2x80x9cconnectorxe2x80x9d includes numerous fiber optic connectors which may have a variety of ferrule configurations, including, for example, an MT, MT-S, MTP, MT-RJ and DC connectors. These optical fiber ribbons have a matrix, including a central optical fiber or a series of optical fibers, that carries information. Surrounding the optical fibers is a protective acrylate primary fiber coating, that in turn is followed by a layer of strength fibers, such as, for example, strength fibers made from Kevlar. Surrounding the strength fibers is a protective outer coating. At each end of the ribbon, it is necessary to attach a terminal connector securely so that information is properly transferred from the optical fiber ribbon through a mating connector or communicating hardware. Therefore, it is imperative that the ribbon is reliably and sturdily connected to the terminal connector so that the information is preserved and properly transferred.
As generally known in the art, the ribbon can be attached to a terminal connector using an adhesive, such as, for example, an epoxy resin. The conventional method makes use of a connector boot that is first placed over a terminal end of the optical fiber ribbon and then followed by a spring, a ferrule boot, and other connector assembly components. Thereafter, the outer coating of the ribbon is removed from the end of the ribbon matrix while preserving the strength fibers lying there beneath. The exposed strength fibers are bent rearward to fully expose the primary fiber coating. Next, a given length of the primary fiber coating is removed to expose a given length of bare optical fibers. Then, the ferrule boot is positioned over the exposed primary fiber coating. The ferrule boot and the exposed ribbon fiber are coupled together using an epoxy resin. Then, the ferrule boot and the exposed strength fibers are securely adhered to a portion of the ferrule or the connector, for example, as described for example in U.S. Pat. No. 5,806,175. Next, a connector pin-clamp is attached to the connector assembly. The pin-clamp can be universal, male, or female, depending on the orientation desired. Finally, the connector assembly is inserted into and coupled with a housing to form the terminal connector.
A ferrule boot serves two primary functions. First, it provides a certain strain relief to the optical fiber ribbon, particularly where no protecting plug hardware is present. Second, it prevents the epoxy resin from flowing out of the connector cavity. As is well know in the terminal connector art, the ferrule boot typically is the first component installed onto the ribbon. The prior art boot is sized and dimensioned to fit intimately over the ribbon, such as, for example, the boots shown in U.S. Pat. Nos. 5,214,730; 5,151,962; 5,329,603 and 5,781,681. Due to the intimate fit of the boot over the ribbon, the protective layers on the ribbon""s matrix cannot be stripped to expose the fragile optical fibers prior to installing the ribbon to the ferrule boot to prevent the optical fibers from breaking. This tight tolerance and the inability to pre-strip the ribbon prior to assembling the connector hinder automated installation efforts. Since large numbers of terminal connectors are manufactured every day, the inefficiencies created by current assembly processes that are less than fully automated quickly result in significantly increased manufacturing times and costs.
Thus, there is a need for optical fiber ribbon connector that is capable of being installed by automated assembly. Further, there is a need in the art for an optical fiber ribbon connector that has improved ribbon retention.
Accordingly, it is an object of this invention to provide a terminal connector that is capable of being automatically assembled.
Another object of this invention is to provide an enhanced boot for a terminal connector that improves automated assembly.
Another object of this invention is to provide an enhanced boot for a terminal connector that improves optical fiber ribbon retention.
These and other objects, features, aspects, and advantages of this invention are realized by a ferrule boot for protecting an optical fiber ribbon connected to a terminal connector. The ferrule boot comprises a body member defining a channel extending therethrough, and a first tapered lead-in located at a distal end of the channel. The first tapered lead-in is sized and dimensioned such that the optical fiber ribbon with the optical fibers stripped and exposed is insertable through the boot from the distal end of the channel to a proximal end of the channel and then is affixed to the ferrule boot by adhesive. The first tapered lead-in is connected to a second tapered lead-in, and the second tapered lead-in prevents the adhesive from wicking to the outside of the ferrule boot.
The channel further comprising a substantially straight section sized and dimensioned to fit intimately over the outside of the optical fiber ribbon. This substantially straight section centers and guides the exposed optical fibers to the center of the proximal end of the channel. The ferrule boot also has a lip positioned proximate to the proximal end of the channel and oriented at an angle with the channel such that the lip functions as a seal and also facilitates easier insertion. In another embodiment, the lip also provides a lower resistance to movement of the optical fiber ribbon from the distal end of the channel to the proximal end of the channel and provides a higher resistance to movement of the optical fiber ribbon in the opposite direction.
The ferrule boot may also have a vent channel in fluid communication between a cavity in the boot and the ambient atmosphere to vent gas trapped in the boot cavity. For example, the ferrule boot cavity may include a vent channel that extends lengthwise along a portion of the interior cavity and that terminates at the proximal end of the boot.